Calculators

Compound Interest CALCULATOR

See how your money grows with compound interest. Add monthly contributions and choose your compounding frequency.

Private by design No signup · Free

Investment Details

Principal Amount ($)

Monthly Contribution ($)

Annual Interest Rate (%)

Time Period (years)

Compound Frequency

What-If

Test different scenarios instantly

History

Growth Results

Estimates for education only — not financial, tax, or investment advice. Verify with a qualified professional. Disclaimer

$0.00

Total Value

$0.00

Total Contributions

$0.00

Total Interest Earned

0.00%

Effective Annual Rate

Year-by-Year Growth

Year	Start	Contributions	Interest	End

Milestones

Time to Double—

Value at End—

Frequently Asked Questions

How does the Compound Calculator work?

Enter lumpsum principal, monthly deposit, annual rate, years and compounding frequency (1/2/4/12), then press Compute. The tool applies FV = P×(1+r/n)^(n×t) plus recurring deposits locally, showing total value, contributions, interest and effective annual rate in a year-by-year table.

Should I choose lumpsum or SIP monthly deposits for faster growth?

Lumpsum benefits from full-period compounding while SIP monthly deposits smooth market timing and build discipline. Enter the same rate and years with P=0 plus $500/month versus P=$50,000 plus $0/month to compare totals, then check Rule-of-72 doubling and effective annual rate to decide.

How does Rule of 72 estimate doubling time?

Divide 72 by your annual rate to estimate years to double — e.g. 8% doubles in about 9 years. The calculator confirms this with exact FV math across annual, quarterly and monthly compounding frequencies, so you can see why higher frequency shortens doubling slightly.

Is my data safe when using Compound Calculator?

Absolutely. All lumpsum, deposit and rate inputs are processed locally in your browser with local-storage memory. Your data never touches any server and is never stored or tracked.

What is compound interest?

Compound interest is interest calculated on the initial principal plus all accumulated interest from previous periods. Your money grows faster over time because you earn interest on your interest — this is called the snowball effect.

How often should I compound my investments?

Higher compounding frequency means faster growth. Monthly compounding earns more than annual, and daily earns more than monthly. Most savings accounts compound daily, while investments like FDs may compound quarterly or annually.

What is the difference between simple and compound interest?

Simple interest is calculated only on the principal amount every year. Compound interest is calculated on the principal plus all interest already earned. Over 10 years at 8%, $10,000 earns $8,000 with simple interest but $11,589 with monthly compound interest.

Can I add monthly contributions?

Yes. Enter a monthly contribution amount and the calculator adds it each month before applying interest. Regular contributions dramatically boost your total value — try comparing $0 vs $500/month to see the difference.

How to Use

Enter Your Numbers

Type your starting principal, monthly contribution, annual interest rate, and time period in years.

Choose Frequency

Select how often interest compounds: annually, semi-annually, quarterly, or monthly.

Review Growth

See total value, total contributions, interest earned, and effective annual rate all at a glance.

How to Calculate

Future value equals P × (1 + r/n)^(n×t) plus monthly deposits compounded each period, where P is lumpsum principal, r is annual rate, n is compounding frequency (1, 2, 4 or 12), and t is years. Effective annual rate equals (1 + r/n)^n − 1. Use Rule of 72 (72 ÷ rate) to estimate doubling time, then compare lumpsum vs SIP growth in the year-by-year table.

About the Compound Interest Calculator

The Compound Interest Calculator is a free online tool that shows how lumpsum principal plus monthly deposits grow with compounding frequency (annually, semi-annually, quarterly or monthly). It calculates total value, total contributions, interest earned, effective annual rate, and annuity-style deposit growth for any rate, time period and SIP vs lumpsum scenario.

Use the Rule of 72 doubling estimate, year-by-year table and What-If milestones to compare deposit strategies. All calculations happen locally in your browser. No data is sent to any server, no sign-up required, and your input values are saved in local storage for convenience between visits.

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Methodology & feedback

Figures run locally in your browser from the values you enter (page updated 2026-10-02). Estimates are educational only — verify finance, tax and health decisions with a qualified professional (see Disclaimer). Spotted an error? Report it via contact and we correct with a new update date.

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